HI,
What is the best router bit for mortising?
cutting diameter? cutting length? overall length?
OMG so much to choose from
3 flute spirals, 2 flute spirals, compression spiral router bits, 0-flute spirals, upcut solid carbide?
what are the most common sizes .. 1/4, 3/8th, 1/2″ that would perform most mortising tasks
wanda
Replies
Mortising bits
Wanda,
The width and depth of the mortise defines the maximum diameter and required cutting length of the bit. Sometimes you may want a smaller diameter bit to reduce the corner radius of the mortise or to provide more clearance between the bit and the guide bushing to facilitate chip removal. Spiral upcut seem to be the bit of chioce for most mortises but straight two flute or straight shear angle bits also work. Greg Paolini recently did a FWW article on 3hp + routers and while he didn't specify the bit design he selected Whiteside because of their performance in earlier FWW router bit tests (FWW 137 and 191 but these were two flute straights cutting grooves in melamine coated particle board and profile bits respectively) Photos in the recent article look as though he used a spiral upcut bit. He did another article on Guide Bushings (FWW 207) and I think he used the spiral upcut in that one as well. Maybe he'll chime in and say exactly what he used and why.
In Bill Hylton's book Router Magic (1996 Rodale Press) he has a chapter on mortising and all the graphics show a spiral bit and I didn't see any recomendation on bit design but there's a lot in that book and I could have missed it. Also lots of terrific jigs with very detailed instructions for all sorts of routing applications. Bob Wearing's book, Router Tips and Techniques (2001 Guild of Master Craftsman Publications) doesn't mention spiral bits and all the photos where the bit is seen are two flute straight cutters.
I use the Leigh MMT and FMT jigs. Leigh recommends and sells upcut spiral HSS and solid carbide bits. Their bits are made by Onsrud and Misenheimer in the US. Very pricey. I normally buy from Leigh but MLCS also makes the longer length bits required by the Leigh jigs.
Resharpening straight fluted cutters is more readily available than for spiral cutters and I've found the resharpend bits often cut better than the OEM edge.
So, I guess there's no simple answer to your bit selection question.
Regis
Mortising with End Mills
Wanda,
Even more options: https://www.finewoodworking.com/item/.../end-mills-vs-router-bits-for-mortising
Regis
mortising bits
up cut spirals all the way. chose a diameter to suit the scale of work you do. for most work a 5/16" x 3-inch solid carbide fits the bill for me. If you work with thick material buy a 3/8" or 1/2" as well.
Robert
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